32310U bearing: complete specifications & equivalents
The 32310U is a ISO 355 radial bearing sized 50 x 110 x 42.25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 50 mm |
| Outer diameter D | 110 mm |
| Width B | 42.25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 204 kN |
| Basic static load rating C0 | 232 kN |
| Fatigue load limit Pu | 28.3 kN |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1920 g |
| Manufacturer designation | NTN 32310U |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 32300-series range
| Bore d | 1.969 in |
|---|---|
| Outer diameter D | 4.331 in |
| Width B | 1.663 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 30 mm |
| Smallest bore in 32300-series | 20 mm |
| Largest outer diameter in 32300-series | 460 mm |
| Width range across 32300-series | 22.25–154 mm |
| Bore position in 32300-series (smallest first) | 8 of 30 |
| Bore above smallest 32300-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32310U | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 32310U model number is decoded
The NTN 2203E table prints 32310U in the extra-heavy 32300 family: 50 mm bore, 110 mm cup OD, 42.25 mm T, with a grease limiting speed of 3,600 r/min and an oil-lubricated ceiling of 4,800 r/min. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 2FD, which is the maker-neutral cross-reference for the 50×110 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. 2203E lists two speed ceilings for 32310U: 3,600 r/min with grease lubrication (the limiting speed) and 4,800 r/min with oil, the higher oil value reflecting better heat removal from the cone rib. The 30.0 mm section height over the 50 mm bore positions the load centre; axial location of the pair depends on that contact line, so spacer faces must be square within the P0 tolerance of the bearing. When pairing 32310U with a second tapered bearing, keep the matched arrangement clean: a single stray grit particle between cup and housing changes preload faster than the adjustment range can correct.
Typical equipment & failure modes
Common applications
- bevel and helical pinion drives with high thrust component
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
- axle final-drive and differential positions
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- cage fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- water-induced pitting when the open bearing is exposed to washdown without external seals
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 50 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 32310U.
- The extra-heavy 32300 family at 50 mm bore (110×42.25 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 4,800 r/min oil ceiling.
- The U/UTG/X/C/CA/D suffix variants of a base number share the bore but not the article: ordering 32310U by size alone can deliver the wrong contact-angle execution for a pinion position.
- On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 50 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
- Grease packs must leave free volume in the 42.25 mm-wide set; over-greasing a paired bearing churning at the 4,800 r/min oil-band speed raises temperature and destroys the preload setting.
- The 204/232 kN ratings and 28.3 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32310U (ISO 355 2FD); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 32310U?
32310U is a metric 4T tapered roller bearing to ISO 355: 50 mm bore, 110 mm outside diameter and 42.25 mm assembled width T (1.969 × 4.331 × 1.663 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 204 kN, C0 232 kN, Pu 28.3 kN, grease limiting speed 3,600 r/min, oil speed 4,800 r/min, mass about 1920 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32310U?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (32310U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32310U designation encode the 50 mm bore and what is 2FD?
last two digits 10 are the ISO bore code, ×5 = 50 mm (codes 00–03 use the 10/12/15/17 exception table). The 110 mm OD and 42.25 mm assembled T follow the ISO 355 dimension-series plan. 2FD is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 32310U list two speeds, 3,600 and 4,800 r/min?
The lower figure, 3,600 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32310U at 4,800 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32310U mean?
Suffix reading on 32310U: U marks the reinforced/uprated internal design of the bare number, a separate order number with higher load capacity than the basic execution; the suffix is part of the order number and the variants are not interchangeable articles.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.